Overview
EN ISO 3382-2:2008 - Acoustics: Measurement of room acoustic parameters - Part 2: Reverberation time in ordinary rooms specifies standardized methods to measure reverberation time in everyday rooms (classrooms, offices, restaurants, workshops, corridors, sports halls, terminals, etc.). The standard defines the measurement procedure, required apparatus, number and layout of measurement positions, data evaluation methods, and reporting format. Results are commonly used to correct other acoustic measurements (e.g., sound pressure level, sound insulation) and to compare with regulatory or design requirements.
Key topics and requirements
- Measurement methods: two principal techniques are specified
- Interrupted noise method (direct recording of decay after noise cutoff)
- Integrated impulse response method (reverse-time integration of squared impulse responses)
- Evaluation ranges: T20 and T30 are defined (reverberation times extrapolated from 20 dB and 30 dB decay ranges). The standard gives preference to T20 for practical field use.
- Accuracy levels: three measurement levels-survey, engineering, and precision-with differing numbers of positions and tolerances to suit time/resources vs. accuracy trade-offs.
- Measurement conditions:
- Rooms should normally be unoccupied (up to two persons may be allowed to represent unoccupied state).
- For precision work, air absorption, temperature, and relative humidity should be measured (large rooms > 300 m3 can show significant air absorption at high frequencies).
- A signal‑to‑noise requirement is noted: achieving a 20 dB evaluation often demands at least a 35 dB SNR.
- Apparatus and filters: band or octave filters per IEC 61260 and suitable microphones/recording equipment.
- Data evaluation & quality checks: procedures for decay-curve fitting, measurement uncertainty (Annex A), and detection of non-linear/curved decays (Annex B). Rotating microphones are only accepted in the interrupted noise method and only when results are used for correction terms.
Applications and users
- Who uses it: acoustic consultants, building acoustics engineers, test laboratories, architects, facility managers, and regulatory bodies.
- Practical uses:
- Verifying and specifying reverberation time for speech intelligibility, music, and comfort.
- Correcting sound pressure level and sound insulation measurements (ISO 140 series, ISO 3740).
- Compliance checks against building codes or design targets.
- Site surveys (quick audits) to full precision measurements for design validation.
Related standards
- ISO 3382-1 - Performance rooms (auditoria)
- ISO 3382-3 - (open plan spaces - in preparation)
- ISO 18233 - Measurement methods in room acoustics
- IEC 61260 - Octave-band and fractional-octave-band filters
Keywords: EN ISO 3382-2:2008, reverberation time, room acoustics, interrupted noise, integrated impulse response, T20, T30, acoustic measurements, building acoustics.
